Transgenic perennial biofuel feedstocks and strategies for bioconfinement

Pollen Sterility—A Promising Approach to Gene Confinement and Breeding for Genetically Modified Bioenergy Crops

“…A major component of gene flow in flowering plants is pollen-mediated transfer [2,9,11,37]. Several field studies and risk assessments have been performed on both annual and/or self-pollinating transgenic crops [25,26,[75][76][77][78] and transgenic herbicide-resistant perennial grasses [12][13][14][15]26,79].…”

“…Therefore, TC has important regulatory, economic, environmental and biosafety implications for the release and commercialization of transgenic bioenergy feedstocks. Various TC strategies have been devised based on hybrid plant systems [2,9,11,17]. The methods for transgenic hybrid plant gene confinement that have been developed so far include seed-based gene confinement, the gene deletor system, and various total sterility concepts.…”

“…One tactic for preventing and/or mitigating transgene flow is the production of nuclear male-sterile transgenic plants incapable of developing fertile pollen carrying transgenes [2]. For instance, physical linkage of a gene encoding a cytotoxic molecule (such as barnase) to a tissue or developmentally-specific promoter could be used to produce male-sterile transgenic plants [2,11]. This type of approach has been well established as an effective strategy for production of male sterility in plants [32][33][34][35].…”

“…This is because many of the traits that are beneficial to the commercial production of perennial plants potentially impact plant fitness and the ability of the plants to compete for resources [6,8]. Confinement of transgenes is thus an obvious regulatory and biosafety objective for the release and commercialization of transgenic bioenergy feedstocks [9,10] as the development of fertile reproductive structures in genetically modified perennial plants will result in undesirable gene flow to non-transgenic and wild plants [9,[11][12][13][14][15][16]. Hence, the control of gene flow is widely understood as a major obstacle to genetic improvement of perennial plants.…”

Benefits and Costs of Biologically Contained Genetically Modified Tomatoes and Eggplants in Italy and Spain

“…This gene flow can be inhibited by physical measures, such as isolation distances between GM crops and conventional varieties or wild relatives, and by biological containment, i.e., by introducing changes in the plant's reproductive systems preventing dispersal of viable seeds and/or outcrossing through pollen. An example of such a containment measure is the control of pollen-mediated gene flow from the plant via transgenic male-sterility systems [3,4]. Hence, biologically contained GM crops do not require the stringent coexistence regulation that exists for regular GM crops in the European Union and are under debate in the US [1,5].…”